Apparatus for laying pipe

ABSTRACT

A method and apparatus for laying pipe in which a cage is provided that can be lowered into a pit in the ground with the cage having spaced side walls and being open at one end and at the bottom while having a longitudinally moveable end wall at the other end. A conveyor system associated with the cage transfers earth excavated at the one end of the cage down to the other end of the cage outside the end wall of the cage and hydraulic motors are provided between the end wall of the cage and the side walls to advance the cage toward the region being excavated while pipe is laid along the bottom of the pit in excavated region below the level of the aforementioned end wall.

United States Patent 1 91 1111 3,820,345 Brecht June 28, 1974 APPARATUS FOR LAYING PIPE 3,729,438 5/1973 Morrice 61/41 A [76] Inventor: Heinz Brecht, Angerbergstrasse 2, FOREIGN PATENTS OR APPLICATIONS Rhemshem Germany 1,152,065 7/1963 Germany 61/41 A [22] Filed: July 14, 1972 Primary Examiner-Jacob Shapiro 2 1] App] No 271374 Attorney, Agent, or Firm-Walter Becker [30] Foreign Application Priority Data TR I July l6, l97l Germany 2l35577 [57] ABS CT A method and apparatus for laying pipe in which a [52] us. Cl 61/41 A, 61/72. 1, 61/72.5 g is provided at a be lowe d into a pit in the [51] Int. Cl E21d 5/00, F161 l/OO, E02f 3/62 ground with the ag a ing spa d side walls and [58] 'Field of Search 61/41 A, 41, 72.2, 72.7, being p one end and at the bottom while having 6]/72 1, 72,6, 725, 63 a longitudinally moveable end wall at the other end.

A conveyor system associated with the cage transfers References Cited earth excavated at the one end of the cage down to UNITED STATES PATENTS the other end of the cage outside the end wall of the 2,922,283 1/1960 Porter 61/41 A cage and hydraulic motors are P v between the 3,212,270 10/1965 Benintend... 61/41 A end Wall Of the g and the side walls. to advance the 3,290,804 12/1966 Hanson 61/72.1 X cage toward the region being excavated while pipe is 3,377,806 4/1968 Morrice 61/41 A laid along the bottom of the pit in excavated region 3,479,827 1 H1969 Morrice 61/41 A below the level of the aforementioned end wall. 3,54l,799 ll/l970 .lost et al.. 61/41 A 3,583,168 6/1971 Horton 6l/72.1 15 Claims, 3 Drawing Figures N -"--'-"-:r\-- A A 7 Pmmmza m4 SHEEIIUFI} WIII. I I I l l APPARATUS FOR LAYING PIPE The present invention relates to a method of and device for sheeting or bracing trenches or ditches and for refilling the trenches or ditches.

The heretofore known method of laying pipes in ditches may be divided into three main steps, namely:

a. Digging the ditch and sheeting or bracing the same.

b. Lowering the pipe into the ditch.

c. Removing the sheeting or bracing and filling in the ditch.

With regard to step a) it may be said that, depending on the type and compactness of the soil and also depending on the depth at which the pipes are to be laid, the ditch is either dug in a continuous operation or is dug stepwise in downward direction. In most instances, the ditch is braced or sheeted along its entire length in order to prevent the ditch from collapsing. The removal of the soil or material may with this kind of construction be effected from the head side of the ditch being dug when the soil or material remains in place or it has to be effected from the side which operation is rather awkward and time consuming. When ground water is encountered, it is necessary, over a certain length, as a rule at least from shaft to shaft, to lower the ground water below the floor of the ditch in order at all to permit the laying of the pipe. In such an instance, the sheeting or bracing must extend approximately from 40 to 50 cm below the floor of the ditch in order to avoid circulation and thereby a washing out of the soil.

With regard to step b), it will then be necessary to place the pipes into the thus prepared ditch, and the required sheeting or bracing may considerably interfere with this operation. In particular with difficult soil it may become necessary to mount the bracing elements so close to each other that at some sections of the ditch it will no longer be possible to lower the pipes to their intended level. In such an instance it will be necessary to move the pipes along the floor of the ditch which operation is, of course, very difiicult and time consummg.

As to step c), it is further necessary, after the pipes have been laid down, to refill the ditch section by section following the removal of the bracing or lining. If the dug out soil or material was placed laterally of the ditch, the soil or material is to this end pushed back or returned into the ditch. If no place was available alongside the ditch for storing the dug out material and the soil and material had to be trucked away, this material or soil must now be brought back by truck. The necessary compacting of the filled-in soil causes considerable difficulties, especially due to the fact that the trench braces do not permit the use of larger compacting or tamping devices. This means that the filled-in soil must be carefully manually levelled which work is time consuming and expensive and which will result in a later sinking-in of the soil.

If the dug out material cannot be placed laterally of the ditch, it must be removed by trucks to another storage place from where it must be returned to the ditch for filling-in the latter. In order to avoid such work requiring soil moving operations, it is also possible to proceed in such a manner that only one ditch section is dug at a time into which the pipes are placed, whereupon the material removed from the head of this ditch section is filled-in at the back end of this ditch section. In such an instance, however, the length of the ditch must be such that there is room enough for maneuvering of the vehicles transporting the material.

Due to the high cost of the ditch bracing and the difficulties encountered in laying the pipes and also due the efforts and costs involved for obtaining a maximum compacting of the filled-in soil, this method of laying pipes in relatively deep ditches is rather time consuming and expensive.

It is, therefore, an object of the present invention to provide a method of and device for bracing or sheeting a ditch and subsequently filling-in the same which will overcome the above mentioned drawbacks while simultaneously increasing the pipe laying speed.

This object and other objects and advantages of the invention will appear more clearly from the following specification in connection with the accompanying drawings, in which:

FIG. 1 is a longitudinal section through the bracing cage or basket.

FIG. 2 is a cross section taken along the line lI-II of FIG. 1.

FIG. 3 is a top view of the device according to the present invention.

The present invention is characterized primarily in that a bracing cage or basket which is open at the bottom and at its front end and the side portions of which correspond to the configuration of the ditch to be dug is lowered into a pit, and is furthermore characterized in that the soil at the front end of the cage or basket is lifted out and by means of a conveyor belt is filled into a shaft at the rear end of the cage or basket where it is compacted by means of hydraulic presses. The said shaft is formed, on one hand, by the filled-in and already compacted earth wall extending at an incline with regard to the horizontal plane at an angle of from 50 to and, on the other hand, by the compacting plates or shields provided at the rear end of the cage. The invention is furthermore characterized in that the pipes are placed upon the floor of the trench or ditch within the cage whereupon the entire cage or basket is advanced by means of the hydraulic presses.

In contrast to the heretofore practiced mode of operation, according to which the pipe laying is carried out in three clearly distinct phases, namely:

The digging of the ditch in the first phase,

the laying of the pipes in the second phase, and

the refilling of the ditch in the third phase, the present invention provides that in a continual working process at the front end of the cage the soil or mate rial is removed and is over a conveyor belt extending along the cage transported to the rear end of the cage while in the interior of the cage the pipes are being laid and at the rear end of the cage the ditch is filled-in again and the filled-in soil or material is at the same time compacted.

The method according to the present invention may advantageously be practiced by means of a cage or basket which consists of two form lining walls which are spaced from each other by a distance corresponding to the desired width of the ditch to be dug and which are supported and braced against each other by means of trench shores and hydraulic cylinder piston systems. According to the present invention, a plurality of such form lining walls may be arranged one above the other while the end faces of the form lining walls extend upwardly at an angle of from 50 to 80 with regard to the horizontal plane. This horizontal subdivision of the cage is not only practical for adapting the cage to the various desired depths of the ditches to be dug, but is even necessary for purposes of transporting the cage. For the same reason it is advantageous also to provide a vertical subdivision of the form lining walls of the cage. In order to avoid that in case of supply lines crossing each other the entire device has to be removed, the uppermost form lining is verticallysubdivided into sections having a width of approximately 50 cm which sections within the region of the supply lines may be pulled upwardly and may again be pushed back downwardly. A very clever possibility of moving the cage into and out of the ditch can be realized by interconnecting the lowermost two form lining walls placed on upon the other by two hydraulic lifting/pulling cylinders each. After the first pair of form lining walls has been put in place and after the second pair has been placed upon the first pair, the uppermost pair can be pressed against the ditch walls by the hydraulic cylinder piston system which spreads the uppermost pair apart whereupon the lower pair can be pushed in downward direction by the lifting/pulling cylinder. Thereupon the lower pair is braced against the side walls of the ditch andthe upper pair is pulled downwardly by the lifting/pulling cylinder. In this way the form lining walls can climb downwardly to the desired depth and additional form lining walls placed thereupon can also be pulled downwardly together therewith. When it is desired to remove the entire device, it is, of course, to be understood that this process is to be effected in the reverse sequence.

In order to assure that the device will always remain at the same level while the cage is being moved, expediently supporting rollers adjustable as 'to height and moving on the trench floor are provided on the lowermost formlining wall portion. For the same purpose, longitudinally extending guiding rails may be provided on the outside of the form lining walls which guiding rails will dig themselves into the soil and will prevent the cage from sinking down.

Expediently, the lowermost form lining wall may be extended beyond the floor of the ditch in the shape of a thin-walled extension by means of which the form lining is bonded into the floor of the trench. This is not only always desired, but is even necessary when ground water is present in order to prevent the floor from being surrounded by water. Moreover, this extension also serves as compensating lining when it is necessary, for instance with supply lines crossing each other, to lower the entire cage over a short distance.

Advantageously, the hydraulic press comprises two superimposed hydraulic cylinders pivotally connected to the form lining walls. These cylinders together drive a shield or plate which is supported by a holding device variable as to length. The shield or plate should be partly perforated in order to allow the air and/or the water to escape during the compacting of the soil. Expediently, the shield or plate is formed by two transverse girders arranged at the rear end of the cage into which individual shield sections are insertable. In this way the shield or plate can be adapted to the respective desired width of the trench to be filled. To obtain a proper compacting result, one or more vibrators may be arranged on the shields or plates.

In order with the mounted form lining walls to save a pair of hydraulic cylinders, it is suggested pivotally to connect the shields of the hydraulic presses of the mounted form lining walls with the shields arranged therebelow. In this way only for the lowermost shield two cylinder pairs are required, whereas for all successive shields only one cylinder pair is needed.

For compacting the soil or material, in this connection the procedure is advantageously such that a precompacting is effected by advancing all of the shields and a postcompacting is effected with turned-on vibrators by advancing each individual shield. This is possible in view of the pivotal connection of the shields arranged one above the other. In order, with this compacting operation, to prevent an escape of the shields in upward direction, unequal sided angle irons are mounted on the outside of the shields so that no vertical forces can be generated by the pressing action.-

Referring now to the drawings in detail, the cage or basket 1 according to the present invention is composed of form lining walls 2, 3, 4 which are placed upon each other. The walls 3 and 4 are subdivided into front form lining plates 2, 3, intermediate form lining'plates 2", 3" and rear form lining plates 2", 3". The uppermost form lining wall 4 is subdivided, with the exception of its rear form lining plate 4", into individual sections 4 which have approximately a width of 50 cm and are supported by I-beams 5. The walls 2, 3 and 4 are reinforced by trench shores 9 which engage vertical struts 6, 7, 8 and I-beams 5. The struts 7 are additionally engaged by hydraulic spreader cylinders 10. Mounted on the lowermost form lining wall 2 are rollers 12 which are adjustable as to height by a spindle 1 l and which engage the floor 13 of the ditch. Between the two lower walls 2 and 3 hydraulic lifting/pulling cylinders 14 are provided. In the particular illustrated condition of cage 1, the form lining walls 2, 3 are connected to each other by screw flanges 15. Also the form lining wall sections 2', 2", 2" and 3', 3", 3" which are located along one plane, are connected to each other. 7

Provided on the rear form lining wall section 2" is a longitudinally variable holding device 16 which comprises pipes of rectangular cross section which telescopically engage each other and which carry a shield 17. Shield 17 is adapted by means of two hydraulic cylinders 18, 19 to be pushed forwardly and backwardly. The cylinders 18, 19, similar to the holding device 16, are arranged in the plane of the form lining wall. The hydraulic cylinders 18, 19 will in this connection rest against bearing blocks 20. Pivotally connected to the lowermost shield 17 are the shields 21 of the additionally mounted form lining walls 3 and 4. To these further shields 21 there are linked merely upper hydraulic cylinders 18. The outer side of shields 17, 21 is provided with an angle iron-shaped fitting 22 which with the lowermost shield 17 extends only to the level of the pipe 23 indicated by dash lines (FIG. 1). Mounted on the inner side of shields 17, 21 are vibrators 24. The shields 17, 21 are adapted by corresponding connecting means to be disengaged from the hydraulic cylinders 18, 19 or the holding device 16 in a simple manner, for instance, when a shaft 25, indicated by dash lines in FIG. 1, has to be built into the pipeline train. In the illustrated position, the front surfaces of the shields 17, 21 form with the horizontal plane an angle of approximately 66. This angle may, depending on the length range of the hydraulic cylinders 18, 19, be varied to suit the best possible slope angle of the respective type of soil.

At the head end of the cage 1, the form lining wall sections 2, 3, 4' are sharpened (26) in order to permit an easy penetration into the soil during the advancement of cage 1. A longitudinally extending conveyor belt 27 which runs on rollers 28 is flanged to cage 1. Mounted on the longitudinal conveyor belt 27 is a filling funnel 29 the bottom side of which is provided with counter rotating fluted rollers 30. This longitudinally extending conveyor belt 27 transfers the material to a transverse conveyor belt 31 which is displaceable along a pair of rails 32 in a direction transverse to the longitudinal direction of the ditch.

For inserting or installing the cage 1 for the first time, a pit must be dug having the desired width of the trench to be dug and having a depth which corresponds to the stability of the respective soil, whereupon the form lining wall 2 must be inserted after it has been reinforced by the trench shores 9. Also the hydraulic spacer or spreader cylinders are inserted in this condition of cage 1. After a further dredging of the pit, also the form lining walls 3 are put in place but are not yet connected to the walls 2. For lowering the form lining walls, the wall pair 3 is by means of the spreader cylinder l0 pressed against the wall of the pit and the lower pair of form lining walls 2 is by means of the lifting/pulling cylinders l4 pressed into the soil. Subsequently, the pair of form lining walls 2 pressed into the soil is by means of the hydraulic cylinder 10 pressed against the wall of the pit and the pair of form lining walls 3 is also by means of the lifting/pulling cylinders 14 pulled downwardly. This cycle is continued until the form lining wall 2 with its rollers 12 rests on the floor of the ditch or until all form lining walls 3, 4 placed one upon the other are located within the pit. The removal of the device is effected in an analogous manner, but in the reverse sequence.

After the cage has been installed, the laying of the pipes 23 may begin. For advancing the trench, a dredge 33 lifts out the material to be removed and empties it into the filling funnel 29. From here the material is on the longitudinal conveyor belt 27 conveyed to the transverse conveyor belt 31 which will empty the material into the shaft between the wall of soil and the shields 17, 21. After this shaft has been filled, the form lining walls 2, 3 are pressed by the spreading cylinder 10 against the wall of the trench whereupon the filledin material is compacted by the shields 17, 21 which are pushed forward by the hydraulic cylinders l8, 19. An additional compacting is obtained by vibrating the material by means of the vibrators 24 mounted on the shields 17, 21, in which instance a stepwise compacting starting with the lower shield 17 is to be recommended. During the compacting operation, the filling funnel 29 collects the material which is being lifted out by the dredge 33.

For advancing the cage 1, the spreader cylinders 10 are disengaged so that the pressure of the hydraulic cylinders 18, 19 will push the respective form lining walls and thus also the entire cage 1 forwardly. During this step, the sharpened portions 26 of the form lining walls 2, 3, 4 will cuit' into the soil so that proper trench walls will be obtained. Following the advancing of cage 1, the cycle is repeated until again a pipe 23 can be laid.

For purposes of providing a shaft 25 (FIG. 1) after the last advancement of the respective shields 17, 21, the shields are disengaged from the hydraulic cylinders 18, 19 and are again behind the shaft installed in the illustrated manner. Expediently, for purposes of building the shaft 25, prefabricated concrete elements are used so that the awkward form lining for the shaft will not be necessary.

FIG. 2 shows a well which ends below-the longitudinal conveyor belt 27. In this way that side of cage 1 or that side of the trench which is located opposite to the longitudinal conveyor belt 27 remains completely free so that the pipes to be laid can be supplied in an unimpeded manner and can be lowered into the trench.

As will be evident from the above, the mode of operation according to the present invention has the following advantages:

a. The trench can be dredged from the head end of the device, in which instance a considerably increased digging speed is obtained and also an improved precision with regard to the digging operation.

b. The side walls of the dug out channel or ditch are braced already during the digging operation so that the digging will present no problems even in case difficult soil conditions prevail.

c. The ditch is properly secured over its entire length necessary for laying the pipe sections because it is considerably simpler to design a short cage so as to be stable than to brace or line several hundred meters of a trench having unevenly extending side walls.

d. The laying of the pipes can be done under optimum conditions because the cage may be so designed that any desired kind of pipes can be lowered into the trench without difficulties and can be assembled on the floor of the trench.

e. The lifted out material can already during the digging be sorted so that only such material may be used for refilling the trench which is suitable for this purpose.

f. The refilling material need not be transported on trucks and, in particular, does not have to be stored.

g. The trench is immediately behind the cage filled in again so that disturbances which are inherent to an open ditch are reduced to a minimum.

h. The material employed for refilling the ditch is immediately compacted uniformly over the entire cross section so that a later settling of the trench need not be feared.

i. The work can be carried out in a continuous and speedy manner inasmuch as the heretofore common three separate working phases have been combined so that it is no longer necessary to wait for the completion of one phase before the next phase can be started.

j. It is also possible to work in three shifts.

k. A coping with ground water has been considerably simplified inasmuch as only the area of the cage itself has to be taken into consideration.

l. The difficult. and dangerous work is not only considerably simplified, but difficult physical labor, as it was heretofore necessary, for instance, in connection with the lining of the trenches and the compacting of the soil, is now taken care of by mechanical devices.

m. The employment of auxiliary labor forces is reduced to a minimum.

The particular advantage of the device and method according to the present invention, in addition to the saved lining or bracing, is seen in the fact that the lifted out soil does no longer have to be transported by vehicles and does not have to be stored. This transporting and storage problem has been solved and taken care of by the conveyor belt which extends laterally of the cage and by an additional transverse conveyor belt at the rear end face of the cage. Both conveyor belts are connected to the cage so that they are advancedtogether with the cage. The material or soil is by a dredge operating at the head of the cage filled directly into a funnel which is provided with counter running fluted rollers or drums. With uniform and favorable soil, also a milling cutter instead of a dredge may be employed, but generally a dredge is recommended because when using a dredge, it is also possible simultaneously to sort the lifted out soil. The filling funnel not only serves as buffer station for the lifted out soil but refines the soil or material to be filled-in at the same time in such a way that it can be filled-in in front of the shields without difficulties and can there be compacted.

The above outlined advantages of the present invention not only greatly simplify and speed up the laying of pipes but also bring about a considerable reduction in the costs involved for the laying of pipes, especially by the saving of labor and time.

It is, of course, to be understood that the present invention is, by no means, limited to the particular showing in the drawings but also comprises any modifications within the scope of the appended claims.

What is claimed is:

1. In an apparatus for use in laying pipe underground, a cage having laterally spaced side walls each comprising superposed sections, at least one fluid operable piston-cylinder means extending laterally between said side walls, an end wall at one end of the side walls and moveable longitudinally relative thereto, and fluid motor means acting longitudinally between saidside walls and said end wall, vertically disposed fluid operable motor connected to a pair of superposed sections to clamp the said sections together, said side walls inclining away from the cage in the upward direction at said one end, said end wall inclining in the same direction, said fluid motor means comprising a plurality of fluid motors distributed vertically along said end wall, the side of the end wall facing away from said cage comprising laterally extending angular steps.

2. In an apparatus for use in laying pipe underground, a cage having laterally spaced side walls, at least one fluid operable piston-cylinder means extending laterally between said side walls, an end wall at one end of the side walls and moveable longitudinally relative thereto, and fluid motor means acting longitudinally between said side walls and said end wall, said side walls inclining away from the cage in the upward direction at said one end, said end wall inclining in the same direction, said fluid motor means comprising a plurality of fluid motors distributed vertically along said end wall, the side of the end wall facing away from said cage comprising laterally extending angular steps.

3. An apparatus according to claim 2 which includes a longitudinal conveyor at the side of said cage and a lateral conveyor at said one end of said cage.

4. An apparatus according to claim 3 in which one end of said longitudinal conveyor is disposed above one end of said transverse conveyor and a hopper disposed above the other end of said longitudinal conveyor.

5. An apparatus according to claim 4 inwhich said transverse conveyor is displaceable transversely of said cage.

6. An apparatus according to claim 2 in which each side wall comprises a plurality of superposed sections, each side wall at said one end inclining upwardly and away, from the cage at an angle of from about 55 to about to the horizontal.

7. An apparatus according to claim 6 in which at least the uppermost one of said sections comprises a plurality of vertically disposed members in side by side relation.

8. An apparatus according to claim 3 which includes vertically disposed fluid operable motor connected to the lowermost pair of superposed sections to clamp the said sections together.

9. An apparatus according to claim 2 which includes supporting roller means mounted on said side walls near the bottom and projecting downwardly therefrom.

10. An apparatus according to claim 2 which includes longitudinal support rails on the outside of said side walls.

11. An apparatus according to claim 2 which includes relatively thin wall elements at the bottom of said side walls extending longitudinally thereof and downwardly therefrom.

12.An apparatus according to claim 2 in which said end wall includes perforation means.

13. An apparatus according to claim 2 in which said side walls comprise superimposed sections and said end wall also comprises sections corresponding to said superimposed sections of the side walls.

14. An apparatus according to claim 2 which includes vibrator means connected to said end wall.

15. In an apparatus for use in laying pipe under ground, a cage having laterally spaced side walls, at least one fluid operable piston-cylinder means extending laterally between said side walls, an end wall at one end of the side walls and moveable longitudinally relative thereto, and fluid motor'means acting longitudinally between said side walls and said end wall, said side walls inclining away from the cage in the upward direction at said one end, said end wall inclining in the same direction, said fluid motor means comprising a plurality of fluid motors distributed vertically along said end wall, said side walls comprising superimposed sections and said end wall also comprising sections corresponding to said superimposed sections of the side walls, the sections of the end wall being pivotally interconnected at the junctures thereof, said fluid motors comprising a laterally spaced pair in about the plane of the juncture of each pair of the sections of said end wall. 

1. In an apparatus for use in laying pipe underground, a cage having laterally spaced side walls each comprising superposed sections, at least one fluid operable piston-cylinder means extendIng laterally between said side walls, an end wall at one end of the side walls and moveable longitudinally relative thereto, and fluid motor means acting longitudinally between said side walls and said end wall, vertically disposed fluid operable motor connected to a pair of superposed sections to clamp the said sections together, said side walls inclining away from the cage in the upward direction at said one end, said end wall inclining in the same direction, said fluid motor means comprising a plurality of fluid motors distributed vertically along said end wall, the side of the end wall facing away from said cage comprising laterally extending angular steps.
 2. In an apparatus for use in laying pipe underground, a cage having laterally spaced side walls, at least one fluid operable piston-cylinder means extending laterally between said side walls, an end wall at one end of the side walls and moveable longitudinally relative thereto, and fluid motor means acting longitudinally between said side walls and said end wall, said side walls inclining away from the cage in the upward direction at said one end, said end wall inclining in the same direction, said fluid motor means comprising a plurality of fluid motors distributed vertically along said end wall, the side of the end wall facing away from said cage comprising laterally extending angular steps.
 3. An apparatus according to claim 2 which includes a longitudinal conveyor at the side of said cage and a lateral conveyor at said one end of said cage.
 4. An apparatus according to claim 3 in which one end of said longitudinal conveyor is disposed above one end of said transverse conveyor and a hopper disposed above the other end of said longitudinal conveyor.
 5. An apparatus according to claim 4 in which said transverse conveyor is displaceable transversely of said cage.
 6. An apparatus according to claim 2 in which each side wall comprises a plurality of superposed sections, each side wall at said one end inclining upwardly and away from the cage at an angle of from about 55* to about 80* to the horizontal.
 7. An apparatus according to claim 6 in which at least the uppermost one of said sections comprises a plurality of vertically disposed members in side by side relation.
 8. An apparatus according to claim 3 which includes vertically disposed fluid operable motor connected to the lowermost pair of superposed sections to clamp the said sections together.
 9. An apparatus according to claim 2 which includes supporting roller means mounted on said side walls near the bottom and projecting downwardly therefrom.
 10. An apparatus according to claim 2 which includes longitudinal support rails on the outside of said side walls.
 11. An apparatus according to claim 2 which includes relatively thin wall elements at the bottom of said side walls extending longitudinally thereof and downwardly therefrom.
 12. An apparatus according to claim 2 in which said end wall includes perforation means.
 13. An apparatus according to claim 2 in which said side walls comprise superimposed sections and said end wall also comprises sections corresponding to said superimposed sections of the side walls.
 14. An apparatus according to claim 2 which includes vibrator means connected to said end wall.
 15. In an apparatus for use in laying pipe underground, a cage having laterally spaced side walls, at least one fluid operable piston-cylinder means extending laterally between said side walls, an end wall at one end of the side walls and moveable longitudinally relative thereto, and fluid motor means acting longitudinally between said side walls and said end wall, said side walls inclining away from the cage in the upward direction at said one end, said end wall inclining in the same direction, said fluid motor means comprising a plurality of fluid motors distributed vertically along said end wall, said side walls comprising superimposed sections and said end wall also comprising sections corresponding to said superimposed sections of the side walls, the sections of the end wall being pivotally interconnected at the junctures thereof, said fluid motors comprising a laterally spaced pair in about the plane of the juncture of each pair of the sections of said end wall. 